As you can see the above query fetch the those department only which has employee and remove the department those doesnt have any.
I can easily able to get the cout of the employees in department using count method.

Sql query :
When you see the Sql profiler or get the query in visual studio by watching variable.

SELECT [t0].[Id], [t0].[Name]
FROM [dbo].[Department] AS [t0]
WHERE EXISTS(
SELECT NULL AS [EMPTY]
FROM [dbo].[Employee] AS [t1]
WHERE [t1].[DeptId] = [t0].[Id]
)